1. Field of the Invention
The present invention relates to a semiconductor device used as a one-sided package device, wherein a multiple-terminal integrated circuit is formed on a circuit substrate, and only one side on which the integrated circuit is formed is sealed by resin.
2. Description of the Related Art
Hitherto, there have been developed one-sided package devices wherein an integrated circuit with not less than 200 terminals is formed on a glass epoxy substrate. The circuit is provided on only one side of the substrate, and that side is sealed by resin. These devices can be manufactured at low cost and easily mounted on a mounting substrate.
The conventional one-sided package semiconductor device will now be explained with reference to the plan view of FIG. 1, the under surface view of FIG. 2 and a sectional view taken along III--III line of FIG. 1.
An integrated circuit 3 with many terminals is adhered to an element portion 1a of a glass epoxy resin substrate 1 with paste 2 such as adhesive agent or solder. One side of the substrate, on which the integrated circuit 3 is formed, is sealed by resin 4.
A plurality of electrode pads 3a are provided on the periphery of the integrated circuit 3. The pads 3a are connected to a plurality of conductive paths 1b by metal wires 5, respectively. The element portion 1a surrounds the periphery of the integrated circuit 3 provided on the upper surface of the glass epoxy substrate 1.
The conductive paths 1b are connected to external terminals 6. The terminals 6 are arranged over the periphery and sides of the upper surface of the glass epoxy substrate 1 and the under surface thereof.
For simplicity, an integrated circuit having only a few terminals is exemplified here.
Since a one-sided package device of the above structure requires only a small amount of resin 4 for sealing, it can be manufactured at low cost. As can be seen from FIG. 4, the one-sided package device of this type can be easily mounted on a mounting substrate by means of surface-to-surface mounting. More specifically, it can be manufactured by connecting the external terminals 6 provided on the under surface of the glass epoxy substrate 1 to the conductive paths 11a provided on the mounting substrate 11 by the solder 12. However, this method results in the following disadvantages.
When a one-sided package device is mounted on a mounting substrate 11, heat is usually applied. Here, asymmetry of the one-sided package device causes a difference in heat conduction, often resulting in connection defects 12a of solder 12.
Specifically, the glass epoxy substrate 1 and the resin 4 differ in heat conduction, and the temperature of the substrate 1 increases more slowly than that of the resin 4. Due to this, the temperature difference between them occurs during the mounting of the device.
Consequently, if the temperature of the external terminals 6 does not increase sufficiently, solder-using connections will become unstable.
Additionally, another conventional one-sided package device wherein bump electrodes 7 are provided on the under surface of the glass epoxy substrate 1 to serve as external terminals, is shown in the plan view of FIG. 5, the under surface view of FIG. 6 and the sectional view of FIG. 7 taken along VII--VII line of FIG. 5. The one-sided package device of this type has similar disadvantages to those mentioned before.
Namely, as shown in FIG. 8, in the one-sided package device having the bump electrodes 7 used as external terminals, when the bump electrodes 7 are connected to the conductive paths 11a on the mounting substrate 11 by bump-like solder 13, there often occurs connection defects such as an unconnected portion 13a or a short-circuited portion 13b. Besides, there is a possibility of water ingress to the interface between the sealing member and the substrate.